DEBT (Details) (USD $) In Millions, unless otherwise specified	1 Months Ended		12 Months Ended				12 Months Ended		12 Months Ended		12 Months Ended		12 Months Ended		12 Months Ended		12 Months Ended				12 Months Ended		12 Months Ended		12 Months Ended		12 Months Ended		12 Months Ended		12 Months Ended		12 Months Ended										12 Months Ended
	Oct. 31, 2010	Sep. 30, 2010	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009	Apr. 30, 2010	Dec. 31, 2011 SunBelt [Member]	Feb. 28, 2011 SunBelt [Member]	Dec. 31, 2011 Guaranteed Senior Secured Notes Due 2017 Series O [Member]	Dec. 22, 1997 Guaranteed Senior Secured Notes Due 2017 Series O [Member]	Dec. 31, 2011 Guaranteed Senior Secured Notes Due 2017 Series G [Member]	Dec. 22, 1997 Guaranteed Senior Secured Notes Due 2017 Series G [Member]	Dec. 31, 2011 Variable -Rate Go Zone Bonds [Member]	Dec. 31, 2010 Variable -Rate Go Zone Bonds [Member]	Dec. 31, 2011 Variable-Rate Recovery Zone Bonds [Member]	Dec. 31, 2010 Variable-Rate Recovery Zone Bonds [Member]	Dec. 31, 2011 Notes payable due 2011 [Member]	Dec. 31, 2010 Notes payable due 2011 [Member]	Dec. 31, 2011 Notes payable due 2013 [Member]	Dec. 31, 2010 Notes payable due 2013 [Member]	Dec. 31, 2011 Notes payable due 2016 [Member]	Dec. 31, 2010 Notes payable due 2016 [Member]	Dec. 31, 2011 Notes payable due 2019 [Member]	Dec. 31, 2010 Notes payable due 2019 [Member]	Dec. 31, 2011 Industrial Development and Environmental Improvement Obligations [Member]	Dec. 31, 2010 Industrial Development and Environmental Improvement Obligations [Member]	Dec. 31, 2010 Recovery Zone Tax-Exempt Bonds due 2035 [Member]	Dec. 31, 2011 Recovery Zone Tax-Exempt Bonds due 2035 [Member]	Dec. 31, 2010 Recovery Zone tax Exempt Bonds due 2033 [Member]	Dec. 31, 2011 Recovery Zone tax Exempt Bonds due 2033 [Member]	Dec. 31, 2011 SunBelt Notes [Member]	Dec. 31, 2010 SunBelt Notes [Member]	Dec. 31, 2011 Tax Exempt Bond [Member]	Dec. 31, 2010 Tax Exempt Bond [Member]	Dec. 31, 2010 Tax Exempt Bond [Member] Tax Exempt Bonds Go Zone due 2024 [Member]	Dec. 31, 2010 Tax Exempt Bond [Member] Tax Exempt Bonds Recovery Zone due 2024 [Member]	Dec. 31, 2011 Interest Rate Swap [Member]	Dec. 31, 2011 Interest Rate Swaps Designated As Fair Value Hedges [Member]	Dec. 31, 2011 Variable Interest Rate Swaps 75M [Member]	Dec. 31, 2011 Variable Interest Rate Swaps 125M [Member]	Dec. 31, 2011 Fixed Interest Rate Swaps 75M [Member]	Dec. 31, 2011 Fixed Interest Rate Swaps 125 M [Member]	Dec. 31, 2011 Industrial Development Obligation [Member]	Dec. 31, 2011 Variable Interest Rate Swap - Due 2016 [Member]	Dec. 31, 2011 Variable Interest Rate Swap - Due 2016 [Member]	Dec. 31, 2011 Fixed Interest Rate Swap - Due 2016 [Member]	Dec. 31, 2011 Fixed Interest Rate Swap - Due 2016 [Member]	Dec. 31, 2011 SunBelt Notes [Member]
Underlying debt instrument [Abstract]
Swap Amount																																						$ 80.8	$ 75.0	$ 125.0	$ 75.0	$ 125.0	$ 7.7	$ 60.0	$ 65.0	$ 65.0	$ 60.0	$ 73.1
Date of Swap																																											March 2002	March 2010	March 2010	October 2011	October 2011	May 2011
Floating interest rate paid (in hundredths)																																											0.81%
Floating interest rate, minimum (in hundredths)																																												3.75%	3.75%	3.75%	3.75%	5.50%
Floating interest rate, maximum (in hundredths)																																												4.75%	4.75%	4.75%	4.75%	6.50%
Gain on variable interest rate swaps																																							7.9	11.0
Amount of gain included in long-term debt						0.3																																		10.5
Fair market value of interest rate swaps																																						2.2
Reduction in interest expense due to interest rate swaps			7.2	7.0	3.0
Notional amount of interest rate derivatives with Citibank																																					7.7
Notional amount of derivatives with Wells Fargo																																					73.1
Revolving credit facility [Abstract]
Available credit under senior revolving credit facility			231.5
Maximum amount of senior revolving credit facility			240.0
Amount of letters of credit issued under subfacility			8.5
Letter of credit subfacility amount			110.0
Expiration date of senior revolving credit			October 2012
Total letters of credit outstanding			34.4
Available letter of credit facility			28.0
Original amount of letter of credit facility			38.0
Long-term debt [Abstract]
Notes payable			536.4	496.0									50.0	14.0	103.0	103.0	0	77.8	11.4	11.4	135.5	129.6	149.0	148.9	10.9	11.3	41.0		42.0		76.6	0		70.0	50.0	20.0
Interest rate swap																		2.8			10.5	4.6			0.3	0.7					1.9
Interest rate										7.23%		7.23%	1.78%	1.76%	1.78%	1.76%		9.125%	6.50%		6.75%		8.875%		6.625%						7.23%
Maturity date of instruments													2024					2011	2013		2016		2019
Minimum maturity date		February 2016													2024										2017						2012
Maximum maturity date		March 2016													2035										2025						2017
Unamortized discount																							1.0	1.1
Amounts due within one year			12.2	77.8
Total long-term debt			524.2	418.2
Drawings on notes																											41.0		42.0				36.0	34.0
Amount of bond proceeds with trustee classified as noncurrent assets			51.7	102.0																								26.0		14.1			11.6
Unamortized fair value premium																															1.6
Industrial revenue bond activity [Abstract]
Redemption of industrial revenue bonds	1.8	18.9
Minimum maturity date		February 2016													2024										2017						2012
Maximum maturity date		March 2016													2035										2025						2017
Premium paid to the bond holders		0.4
Deferred gain recognized						0.3																																		10.5
Interest rate swaps termination date		April, 2010
Maturity date of additional bond redeemed	October 2014
Required annual debt repayment for Series O and Series G notes							12.2		6.1		6.1
Long Term Debt Repayments [Abstract]
Long-Term Debt Repayments			(87.2)	(20.7)	0												75.0														12.2
Business Acquisition [Line Items]
Required annual debt repayment for Series O and Series G notes							12.2		6.1		6.1
Face amount of senior secured notes										97.5		97.5
Interest rate										7.23%		7.23%	1.78%	1.76%	1.78%	1.76%		9.125%	6.50%		6.75%		8.875%		6.625%						7.23%
Long Term Debt Repayment [Abstract]
Long-Term Debt Repayments			(87.2)	(20.7)	0												75.0														12.2
Fair value of acquired debt								87.3
Remaining principal balance of consolidated notes								85.3
Accounts receivable facility [Abstract]
Accounts Receivable Facility				75.0
Renewable period of account receivable facility (in years)				five
Expected maturities of long-term debt [Abstract]
2012			12.2
2013			23.6
2014			12.2
2015			12.2
2016			147.7
Thereafter			$ 328.5